An internal gear pump includes: an internal gear (outer rotor) formed to have an annular shape and have internal teeth; an external gear (inner rotor), having external teeth that can mesh with the internal teeth, provided on the inner circumference side of the internal gear; and a housing that rotatably accommodates and holds the internal gear and the external gear. A plurality of meshing gaps (pump chambers) are defined between tooth surfaces of the internal gear and the external gear along a rotation direction of the internal gear. Each pump chamber rotationally moves in accordance with rotation of the internal gear and the external gear, in mesh with each other, to have a volume repeatedly increased and decreased through movement from one tooth to the other. In the housing, an intake port in communication with an intake area, in which the volume of the pump chamber increases in accordance with the rotation of the gears, is formed, and a discharge port in communication with a discharge area, in which the volume of the pump chamber decreases in accordance with the rotation of the gears, is formed. A fluid taken into the pump chamber through the intake port is sent from the intake area to the discharge area due to the rotation of the gears, to be discharged through the discharge port.